JPS6153564A - Surface image detector by ultrasonic flaw detection - Google Patents

Abstract

PURPOSE:To detect a clear surface image of an object to be inspected efficiently with an automatic correction of variations in the received signal due to irregularities of the surface thereof, by detecting gage points set in a scan area of the surface of the object being inspected with a probe to correct the voltage gain of an amplifier by a differential voltage obtained in comparison with the detection voltage with a reference voltage. CONSTITUTION:A recess 20 exists in an object 1 to be inspected within a closed outer shell and gage points are provided at the positions Y1-Y1 and Y2-Y2. Horizontal position by scanning with a probe 4 is detected with Y and X direction position detectors 12 and 13 to be inputted into an X-Y recorder 14 while an output position signal of the detector 12 is inputted into a operation control circuit 21. The circuit 21 detects rising and falling voltage levels at gage points Y11, Y21-Y22 and the like, compares an input peak value 10 with a reference voltage from a reference voltage setter 23 by a correction detecting circuit 22 at the position to correct the amplification factor of a controllable amplifier 24 by the resulting differential voltage. The ultrasonic signal thus corrected is inputted into the recorder 14 via waveform conversion circuit 15 having the reference voltage as threshold to turn surface irregularities of the object 1 being inspected into an image.

Description

[Detailed description of the invention] [Technical field to which the invention pertains] The present invention relates to a surface image detection device for displaying an image of the state of the surface of a specimen covered with an opaque outer shell etc. using an ultrasonic flaw detection method. The present invention relates to a detection device including an ultrasonic signal correction means for correcting a decrease in sound pressure of an ultrasonic signal due to an outer shell.

[Prior art and its problems]

FIG. 3 is a diagram illustrating the principle of a conventional surface image detection device for the surface of a subject using an ultrasonic flaw detection method. In the figure, reference numeral 1 denotes a flat plate-shaped test object horizontally immersed in water 2, with markings 6 such as ABC on its surface. Reference numeral 4 denotes a probe, which is partially immersed in water and is controlled to move horizontally while maintaining a predetermined probe distance between it and the surface of the subject 1 so that the ultrasonic beam 5 is focused on the surface of the subject 1. transmits an impulse-like ultrasound beam 5 to the surface of the object 10 following a scanning path indicated by a zigzag arrow 6, and receives reflected ultrasound waves from the surface of the object 10 and converts them into electrical signals. . 7 is a flaw detection-like control observation section,
An impulse voltage is applied to transmit an ultrasonic wave, and the signal received by the probe 4 is amplified, and a voltage pulse waveform 9 with a peak value proportional to the sound pressure level of the transmitted and received ultrasonic waves is transmitted to the cathode ray tube.
, 10 and the propagation time t, and by setting the time width of the gate pulse 110, only the ultrasonic signal 10 corresponding to the reflected wave from the surface of the object 1 is output to the external circuit. It is configured so that it can be done. Reference numerals 12 and 13 designate position detectors for the probe 4, such as potentiometers, which output position signals with voltage values directly proportional to the amount of movement of the probe 4 in the Y direction and the X direction, respectively. Reference numeral 14 denotes a display device such as an X-Y recorder, which receives output position signals from the Y-direction position detector 12 and the X-direction position detector 16, moves the pen position to a position corresponding to the probe position, and displays the waveform. The vertical movement of the υ pen is controlled by the ultrasonic signal 10 converted into an on/off signal by a conversion circuit 15. Assuming that the surface of the object to be examined is smooth and that there are only irregularities at the markings 6, the ultrasound beam 5 is diffusely reflected at the uneven parts and the sound pressure of the ultrasound received by the probe 4 is reduced. Therefore, the peak value of the output ultrasonic signal 10 of the control observation section 7 also decreases. Therefore, by observing the wave height value of the ultrahigh wave signal 10, it is possible to detect irregularities on the surface of the subject. Normally, a threshold value is provided in the conversion circuit 15 in order to clearly distinguish the unevenness of the surface, and the ultrasonic signal 10 is turned on or off depending on whether or not it exceeds this threshold value.
By converting it to an off signal and controlling the vertical movement of the pen of the X-Y recorder! The recording section of the J, XY recorder 14 can display or record a subject surface image such as 16.

The surface image detection device using ultrasonic flaw detection is based on the above-mentioned principle, but the object of this invention is stored in an opaque outer shell filled with water etc. in a state that cannot be taken out. This system attempts to externally detect and image the surface conditions and defects of the specimen being inspected.For example, it is used in reading devices for markings on fuel rods in nuclear reactors, flaw detection devices for fuel rods, etc. Applicable.

FIG. 4 is a conceptual diagram for explaining problems with surface image detection devices, typified by marking reading devices.

In the figure, the subject 1 is housed in a cylindrical container 17 made of gold FA filled with water 2, and the cylindrical container 17 is further immersed in water 2 at the free water surface. The probe 4, which is partially immersed in water, performs scanning flaw detection in the Y direction and the X direction (referred to as the water immersion method) in the same manner as shown in FIG. 6, and detects an image of the surface of the object 10. The probe 4 scans in the paper back direction (Y direction) at the X position, then moves to the X1 position and scans in the front direction (Y direction). In the case where the oscillated ultrasonic beam 5A is perpendicularly incident on the wall of the cylindrical container 17, and the ultrasonic beam 5B reflected from the surface of the object 1 passes through the wall of the cylindrical container 17 perpendicularly and reaches the probe 4. The sound pressure drop of the ultrasonic beam at the instrument wall is small, and the probe 4
A receiver of sufficient size (fi times the signal can be obtained, but the probe 4
is at the X7 position, and when the ultrasonic beam is transmitted and received by obliquely entering or passing through the wall of the cylindrical container 17, the transmitting ultrasonic beam 5A is reflected in the a direction from the outer surface of the cylindrical container 17. The reflected ultrasonic beam 5B generates a reflected wave in the b direction on the inner surface, and double reflection occurs on the instrument wall, transmitting it through the instrument wall and hitting the surfaces of the probe 4 and the object 1. This results in a problem in that the sound pressure of the ultrasonic beam transmitted and received between the two ends is significantly reduced. The sound pressure received by the probe 4 may have changed each time the position of the probe 4 in the X direction changes in this way.
Changes in the sound pressure received by the probe 4 due to irregularities on the surface of the subject 1 cannot be detected and imaged. Therefore, in conventional devices, the amplification factor of the received signal amplification circuit of the control observation section 7 is manually adjusted every time the position of the probe 4 in the X direction changes. In order to display an image, it is necessary to adjust the amplification factor extremely many times, which hinders efficient screen display. There was a drawback that images could not be obtained.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned situation, and is capable of automatically correcting fluctuations in received ultrasound signals caused by irregularities on the surface of a subject, and thus can efficiently detect and display a clear image of the surface of the subject. The purpose of this invention is to provide a surface image detection device using ultrasonic flaw detection.

[Key points of the invention]

The present invention provides an operation control circuit that detects the voltage level of a position signal when a probe passes through a reference point position set in advance around a scanning area on the surface of a subject to be imaged, and issues an operation signal. In response to this operation signal, an amplification factor correction value detection circuit takes in the ultrasonic signal, compares it with the standard voltage, and generates a differential voltage signal necessary for the amplification factor #iii, and uses this differential voltage signal to A controllable amplification circuit whose amplification factor is corrected and a conversion circuit which compares the output ultrasonic signal of the controllable amplification circuit with the standard voltage and converts it into an on/off signal are used to perform a probe within the scanning area. This system corrects the drop in sound pressure caused by the outer shell of the ultrasonic signal from the surface of the subject that is received by the sensor, making it possible to clearly and efficiently detect and image irregularities on the surface of the subject.

[Embodiments of the invention]

The present invention will be explained below based on one embodiment.

FIG. 1 is a block diagram showing the configuration of a surface image detection device showing an embodiment of the present invention. In the figure, 1 is the subject;
The cylindrical container 17 in FIG. 4 is omitted to show a mock diagram in which the surface of the subject is visible, and it is assumed that the surface of the subject 1 has a linear recess 20. Y 1-Yl
, Y, -Y are the gauge points set in advance at both ends of the scanning area of the probe 4 in the Y direction, and the first Y□ position on the scanning line shown in a zigzag shape with a dotted line is the position of the probe 4. The first amplification factor correction is performed when Y,1. Position the gauge points of Yl, , Y, etc. with probe 4.
The horizontal position of the probe 4 is not shown in the figure.The horizontal position of the probe 4 is not shown. Y-direction position detector 12 that emits a position signal directly proportional to the amount of movement
．． A position signal output from the Y-direction position detector 13 is output to the X-Y input terminal of the X-Y recorder 14, and an output position signal from the Y-direction position detector 12 is input to the operation control circuit 21.

The operation control circuit 21 detects, for example, the rising voltage level Vx of the position signal at the probe position Yll and the falling voltage level Vd of the position signal at the Y21 position, and generates an operating signal of a constant voltage during this period. A shaping circuit or the like is used. The output operation signal of the operation control circuit 21 is input to the correction value detection circuit 22, and the output operation signal of the operation signal is inputted to the correction value detection circuit 22. In addition to capturing the sonic signal 10, the wave height value of the ultrasonic signal 100 and the standard voltage setting device 2
It is configured to compare the voltage with a standard voltage (8) set in advance by 3 and output the difference voltage. That is, the correction value detection circuit 22 detects the probe position Y11+Y21.
Alternatively, the ultrasonic signal 10 at the gauging positions such as Yll, y**, etc. is compared with the standard voltage, and the reduction in sound pressure level due to the cylindrical container 17 at each probe position is determined from the voltage difference. If the standard voltage is set to be equal to the peak value of the ultrasonic signal 1o of the smooth surface at the X1 position (vertical incidence) in Fig. 4, for example, the sound pressure level will decrease at other positions (for example, X). A differential voltage signal proportional to the amount can be output. 24 is a controllable amplifier whose amplification factor is automatically controlled by a differential voltage signal, and the amplification factor is adjusted so that the peak value of the ultrasonic signal 1o at the gage position set on the smooth surface of the object 1 is equal to the standard voltage. (voltage gain) is corrected. Controllable amplifier circuit 2
The ultrasonic signal whose peak value has been corrected in step 4 is input to a waveform conversion circuit 15 that uses the standard voltage as a threshold, and when the ultrasonic signal exceeds the standard voltage, it becomes an on signal, and when it is below the standard voltage, it becomes an on signal. is converted to an off signal (no signal), and X-Y
This signal is input to the recorder 14, and the vertical movement of the recording pen is controlled by this signal. Now, when the probe 4 moves along the scanning path shown by the dotted line in the figure and reaches the recess 20, the ultrasonic beam is scattered by the recess and the sound pressure level of the reflected wave decreases. The output ultrasonic signal of the control amplifier circuit 24 is lower than that at other locations. Therefore, the conversion circuit 15
The output becomes an off signal, and the portion corresponding to the recess 20 becomes unrecorded 61 in the record 60 of the recorder 14, making it possible to image irregularities such as markings on the surface of the subject 10, for example. In particular, by correcting the decrease in the sound pressure level of the ultrasonic beam due to obstacles such as a cylindrical container surrounding the subject 1 by using the circuit configured as described above, It is possible to image as clearly as if there were no intervention, and since there is no need to manually perform corrections as in conventional devices, it is possible to efficiently and accurately image.

FIG. 2 is a signal waveform diagram showing the operation of each part in the embodiment of the present invention shown in FIG. In the figure, waveform W1
2 is the output position signal waveform of the Y-direction position detector 12. As the probe 4 moves (horizontal axis), the voltage increases in the direction from Y1 to Y, in proportion to the amount of probe movement; , → In the Y1 direction, the voltage value decreases in inverse proportion to the amount of movement. Waveform W21
is the output operation signal waveform of the operation control circuit, and at W12, the scanning time from Y0□→Y□ is determined by a waveform shaping circuit whose threshold voltages are the rising voltage 'bt at the probe position Yll and the falling voltage Vd at the Y21 position. This signal is converted into a rectangular waveform operation signal with a time width that corresponds to the period of time. The waveform W22 is the output difference voltage signal waveform of the correction value detection circuit 22. For example, the rising edge and falling edge of the operating signal W21 are detected and converted into a one-shot pulse with a predetermined pulse width. One or several ultrasonic signals 10 are received by logical product with the ultrasonic signal 10 from the control observation section 7, and this ultrasonic signal 10 is compared with the standard voltage v8 from the standard voltage setting device 23. It can be configured to output the differential voltage ΔV. W24 is the output ultrasonic signal waveform of the controllable amplifier circuit 24, and the amplification factor (
For example, the standard voltage v
The wave height values of the ultrasonic signals repeatedly input at and after the Ys1 position, where there was a voltage difference of ΔV with respect to the Ys1 position, are also corrected to a level equivalent to the standard voltage of 7 days. In addition, the ultrasonic beam is diffusely reflected in the part corresponding to the recess 20 on the surface of the object 1, so that the wave height value of the ultrasound signal is lower than that in other parts. It can be detected as a difference in the peak values of The waveform W30 is converted into an on/off signal by the waveform conversion circuit 15, and
- A signal waveform converted into a vertical movement signal of the pen of the Y recorder 14. The ultrasonic signal in the recess 20, which is lower than the standard voltage v8, is an off signal ML (no voltage) K, and the ultrasonic signals in other parts are Converted to on signal VH, X-Y recorder 1
The linear recording in step 4 is controlled intermittently by the above-mentioned on/off signal, and the uneven portions on the surface of the subject are classified as unrecorded (white) or recorded (for example, black) from the smooth portions, and a black-and-white surface image is created. The surface condition can be detected as follows.

Note that the standard voltage in the waveform conversion circuit 15 is divided into multiple stages to convert the ultrasonic signal into multiple types of on/off signals corresponding to the depth of unevenness on the surface of the subject, and this signal is converted into a multiphenomenal type X- If the information is configured to be input to the control circuits of a plurality of pens of the Y recorder, it is possible to display the surface image of multicolor printing in which the size distribution of the unevenness can be differentiated by color.

〔Effect of the invention〕

As described above, the present invention uses a probe placed outside the outer shell to maintain a predetermined probe distance to obtain a surface image of a subject covered by a sealed outer shell and invisible to the naked eye. For items detected and displayed using water immersion ultrasonic flaw detection method,
An operation control circuit that detects the position of the gauge set around the area to be imaged and issues a control signal, and this control signal captures the ultrasonic signal at the position of the gauge and compares it with a standard voltage to generate a difference voltage signal. A voltage gain correction means is provided, which includes a correction value detection circuit that outputs a voltage difference signal, and a controllable amplifier circuit whose voltage gain is corrected based on this differential voltage signal. As a result, the wave height value of the received ultrasonic signal whose sound pressure (voltage value) has decreased due to the reflection of the ultrasonic beam on the inner and outer surfaces of the outer shell can be automatically corrected by the amount of the sound pressure drop at the outer shell. As a result, the influence of the outer shell is eliminated, and only the irregularities on the surface of the object i can be detected as the distribution of wave height values of the ultrasound signal. It is configured to convert the peak value distribution of the unlimited sound wave signal into an on/off signal and input it to the print control section of the X-Y recorder, and to control the horizontal position of the pen using the X and Y position signals of the probe. Thereby, it is possible to provide a surface image detection device using ultrasonic flaw detection that can display the unevenness distribution on the surface of the object as a surface image. The surface image detection device configured in this way eliminates the need for voltage gain correction, which was conventionally performed manually every time the position in the X direction changes, so the human power and time required for surface image detection are significantly reduced In addition to increasing the striping efficiency, the distance between the zigzag scanning lines, or in other words, the scanning line density, can be increased, resulting in the advantage that clear images can be displayed in a short time. In addition, by correcting the voltage gain using an electronic circuit, the correction granularity can be increased compared to conventional manual operation, and the peak value of the ultrasonic signal can be divided into multiple stages and converted into on/off signals, so it can be used for multiple phenomena. By using the X-Y recorder, it is possible to obtain a multicolor surface image in which the size of unevenness on the surface of the subject can be distinguished by color.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a surface image detection device showing an embodiment of the present invention, FIG. 2 is a signal waveform diagram in the embodiment of FIG. 1,
FIG. 6 is an explanatory diagram of the principle of a conventional surface image detection device using an ultrasonic flaw detection method, and FIG. 4 is a mock diagram for explaining problems in the conventional device. 1... Subject, 2... Water, 6... Stamp, 4...
Probe, 5... Ultrasonic beam, 5A... Transmission wave, 5
B... Reflected wave, 6... Scanning line, 7... Control observation unit, 1o... Reflected ultrasonic signal, 12.13... Position detector, 14... X-Y recorder, 15... Waveform conversion circuit, 17... Outer shell (cylindrical container), 21... Operation control circuit, 22... Correction value detection circuit, 23... Standard voltage setting device, 24... Possible Controlled amplification;. Circuit, Yll, Y, 1. Y, , Y,, ,,
, gauge position, vs - standard voltage. ! Lj-1 in Place Y++ Y21 Fig. 2

Claims (1)

[Claims] 1) An ultrasonic signal corresponding to the reflected ultrasound from the surface of the object that is converted into an electrical signal by a probe whose movement is controlled in the horizontal direction so as to maintain a predetermined probe distance above the object immersed in water. and X of the probe output from the position detector
, and a Y position signal as input signals, the operation of displaying a surface image of a subject using an image display device that uses the position signals as input and generates an operation signal each time the probe passes a predetermined reference point. a control circuit, an amplification factor correction value detection circuit that receives the operating signal, takes in the ultrasonic signal, compares it with a standard voltage, and generates a difference voltage signal; and a controllable amplifier whose amplification factor is corrected by the difference voltage signal. and a conversion circuit that compares the output ultrasonic signal of the controllable amplifier circuit with the standard voltage and converts it into an on/off signal. Surface image detection device using ultrasonic flaw detection method.